Commuters in the San Francisco Bay Area have more to worry about than missing the train. Officials are warning that they may have been exposed to the measles.

A college student infected with measles traveled on BART, the Bay Area Rapid Transit system, from Feb. 4 through Feb. 7 to and from the University of California Berkeley campus. Anyone who rode BART or was on campus during that time has been advised to watch out for symptoms.

"Measles is a serious, highly contagious disease," Dr. Janet Berreman, a City of Berkeley health officer, said in a statement. "It spreads through the air, when an infected person coughs or sneezes. Fortunately, the measles vaccine is highly effective in preventing infection."

The student was not vaccinated against the measles, and was likely infected while traveling abroad, according to a Contra Costa Health Services press release. The student was traveling from UC Berkeley to Contra Costa County, just outside the Berkeley city limits.

The MMR vaccine -- for measles, mumps and rubella -- is not required for UC Berkeley students, according to University Health Services spokeswoman Kim Jarboe LaPean. The school only requires that students be vaccinated against hepatitis B, she told ABCNews.com.

“We strongly recommend all new incoming students have the MMR vaccination,” she said.

No other measles cases have been identified in the Bay Area so far, Jarboe LaPean said.

The United States experienced a spike in measles cases last year, getting more than triple the usual number of cases, according to the U.S. Centers for Disease Control and Prevention.

Measles starts out with flu-like symptoms, such as fever, runny nose and sore throat, but then "tiny white spots with bluish white centers" appear inside the mouth, according to the CDC.